Piston pumps



Dec. 29, 1964 Filed Feb. 12, 1962 w. KUNZLER ETAL 3,163,121

PISTON PUMPS 2 Sheets-Sheet 1 Fig. 1

Dec. 29, 1964 w. KUNZLER ETAL 3,163,121

PISTON PUMPS Filed Feb. 12, 1962 2 Sheets-Sheet 2 Fig. 2

United States Patent Ofifice 3 ,l 3,1 2 l Patented Dec. 29, 1964 3,163,121 PISTQN PUMPS Werner Kiinzler, Munich, and Karl Knauer, Gauting, near Munich, Germany, assignors to Motorenfabrik Hatz G.m.h.H., Ruhstorf, near Passau, Germany, a company of Germany Filed Feb. 12, I962, Ser. No. 172,685

Claims priority, application Germany, Feb. 27, 1961,

11 Claims. (Cl. 103-474) This invention appertains to piston pumps, and has reference particularly .to liquid supply pumps of the kind comprising a pump housing enclosing a drive shaft, and a plurality of, e.g. four or more, purnp units secured to the periphery of the housing and extending radially with respect to and at relatively ofiset positions along, the axis of the said shaft, the said pump units being furnished with delivery pistons which are successively driven from a single eccentric on the drive shaft through the medium of intermediate rings embracing such eccentric.

The obiect of the invention is to provide, in a piston pump of this kind, a driving arrangement which enables the pump to be used as a high-pressure delivery pump whilst at the same time allowing the delivery pistons to be in the form of simple sliding components, i.e. pistons without rollers.

According to the invention there is provided a piston pump of the kind herein referred to, wherein the pump units are arranged in pairs relatively offset along the axis of the drive shaft, the two units of each such pair being diametrically opposite to one another or substantiall so, and the intermedite rings are so arranged side by side that each of them has only the delivery pistons of one pair of opposed pump units bearing thereon so as to be driven thereby.

In accordance with a further feature of the invention, the intermediate rings may advantageously be mounted upon rolling bodies interposed between the eccentric and the said rings. In addition, the intermediate rings may conveniently be maintained in their correct positions on the eccentric, i.e. axially with respect to one another and the pump housing, by means of spacing plates or/ and axial thrust bearings.

In order that the invention may be more clearly understood, and readily carried into practical effect, the foregoing and other features of the invention as embodied in a practical form of the improved piston pump will now be described with reference to the accompanying drawings, wherein FIGURE 1 is a longitudinal section on the line I'-I of FIGURE 2 of the said piston pump.

FIGURE 2 is .a cross section on the line IIII of FIG- URE 1 showing the pump housing per se.

In FIGURE 1 there is shown a pump housing I, which is preferably of cylindrical shape and has rotatably mountted therein a drive shaft 2 provided with an eccentrio 2a. Ball bearings 3 and 4 are interposed between the pump housing I and the drive shaft 2.

Four pump units, arranged to extend radially with respect to the axis of the drive shaft 2, are mounted upon the periphery of the pump housing 1 and are fixedly secured to the latter by screws (not shown), the bearing face of each pump unit being seated in a recess formed in a corresponding face of the pump housing 1. For convenience in the following further description, the four pump units will be designated 5 5 5 and 5 respectively, and the recesses in which they are located will be similarly designated la 141 1:2 and 161 respectively. In FIGURE 1, one only of the pump units, viz, the unit 5 is fully shown, the units 5 and 5 being only partially indicated and the unit 5 being omitted in this same figure; as to the recesses, all four of them are shown in FIG- URE 2 and only the recess Ia in FIGURE 1.

A valve unit 6 having a T-shaped suction valve 611 and a compression valve 6b, also T-shaped, is accommodated in each of the pump units 5 5 5 and 5 In addition, a piston sleeve '7 is housed within each pump unit and receives a delivery piston. The four delivery pistons of the units 5 5 5 and 5 will, in the following description, be designated 8 8 and 8 respectively, pistons S and 8 only being shown in the drawings (see 'FIG- URE 1).

The valve units 6 and the pistons sleeves 7 are secured firmly in the pump units by means of nuts 9. A return spring 10 is interposed between each nut 9 and a spring plate 11 mounted on the corresponding piston.

A central suction chamber is surrounding the drive shaft 2 is provided in the pump housing 1 and is sealed off from the outside by means of a sealing ring 1b arranged to bear against the drive shaft. Each of the pump units 5 5 5 and 5 has a suction duct 5s therein which is connected through a corresponding duct ls in the pump housing 11 to the central suction chamber is. A central compression chamber id in the form of an internally screw-threaded countersunk bore, co-axial with the suction chamber is, is also provided in the pump housing 1. Moreover, a compression duct 5d, provided in each pump unit, is connected, through a connecting duct M in the housing I, with the central compression chamber Id. In the illustrated example, therefore, four suction ducts Is open into the central suction chamber is, and four compression ducts ld open into the central compression chamber Id. The suction and compression chambers are provided respectively with connecting nipples ls and ild of known type (and therefore not shown in detail), the connecting conduits Is and ld thereof being adapted for connection to a liquid supply container and the utility point respectively. For the sake of simplicity in the drawings, these connecting nipples are depicted as having the same dimensions; in high pressure pumps of about 500 atmospheres, however, the connect ing suction nipple 1s and its conduit ls are designed to have a flow passage of greater cross-section than the compression conduit ld Thus, a central suction chamber and a central com pression chamber, both common to all the units, are provided in the pump housing, the suction and compression ducts Is and Id respectively running into the individual pump bodies and being connected to the suction and compression chambers is and 1d respectively by conduits machined in the pump housing. At the same time, a single suction connection, which connects the suction chamber with the supply container, and a single compression connection, which connects the compression chamber with the utility point, are provided in the pump housing.

By virtue of this construction there are no external exposed connecting conduits between the individual pump units or even between the pump housing and the pump units, since all of these connections can be made inside the pump housing. Thus, not only are expensive high-pressure connecting conduits eliminated but, at the same time, leaky and dirty points on the pump are avoided and the pump has, moreover, a closed well-shaped construction, the assembly and operational servicing thereof being capable of being undertaken simply and with easy access.

The sealing of the conduit system between each of the pump units 5 5 5 and 5 and the pump housing 1 is likewise solved in a very simple manner. A sealing ring 18 of copper or the like is inserted in a recess at each joint between connecting ducts M and 5d, said sealing ring being compressed during sealing and tightening down of the relevant pump unit on the pump housing, thereby sealing off the compression condui-t system from the suction side and the outside. A groove 16 is cut in the bearing face of each of the pump units 5 5 and 5 this groove being concentric with the corresponding delivery piston 8 8 8 or 8 and accommodating a rubber sealing ring 17 which seals off the suction side from the outside.

The individual pump units are, as will be apparent from a consideuation of FIGURE 2, relatively disposed in a cruciform arrangement about the periphery of the pump housing 1. The pump units 5 and 5 are arranged diametrically opposite each other. The pump un t 5 is accordingly arranged at an angle of 90 to the unit 5 and is offset to the right by approximately 20 mm. in the axial direction of the drive shaft 2 (see FIGURE 1),

the pump unit 5 (omitted from the drawing) also lying diametrically opposite the unit 5 Two intermediate rings 12 and 12 are mounted side by side for free rotation on the eccentric 2a of the drive shaftZ, with two roller bearings 13 interposed between the rings and the eccentric. Two spacing plates 14 and three axial thrust roller bearings 15 secure the intermediate rings 12 and 12 in their axial positions relatively to each other, to the pump housing 1 and to the drive shaft 2. Each of the roller bearings 13 and 15 comprises a plurality of slender rollers or needles which are contained in the known way in a cage; such bearings are only diagnammatioally illustrated in the drawings.

The pistons 8 and 8 bear directly against the intermediate ring 12 whilst the pistons 8 and 8 bear directly against the intermediate ring 12 the pistons therefore being moved radially in and out on rotation of the drive shaft to deliver the liquid or the like, the stroke of each piston-corresponding to the degree of eccentricity of the eccentric 2a.

Thus, in the driving arrangement described according to the invention, each intermediate ring 12 12 is only engaged by two of the four delivery pistons, of which only one'is driven in the delivery stroke whilst the other is merely in a non-loaded position under the effect of the relevant return spring 10. In FIGURE 1, for example, the piston 8 is having imparted to it its delivery stroke with the result that the intermediate ring 12 is almost checked under the action of the high delivery pressure, for example 200 atmospheres, below the piston 8 and only the roller bearing 13 corresponding to the ring 12 rolls between the latter and the eccentric 2a. The ring 12 thus oscillates and slides over the opposite piston 8 which is at this time neither delivering nor under pressure. This is advantageous in view of the small pressure between the pressure-free piston 8 and the ring 12 The same cycle is also performed, between the ring 12 and pistons 8 and 8 as soon as the eccentric 2a has turned through a further 90 in the clockwise direction. Thus, individual pump units deliver in the cycle l-2-34, the delivery 1-3 being initiated by the intermediate ring l2 and the delivery 2-4 by the intermediate ring 12 Thus, in the arrangement according to the invention scarcely any relative sliding movement between the piston and the relevant intermediate ring occurs in a pump unit which is directly delivering and is under high pressure. A frictionless and wear resisting type of drive is thereby produced which operates in a reliable manner, even in the case of very high delivery pressures (56G atmospheres),

and without piston seizure or the like and is, moreover,

very simple to produce and assemble. The parts 12, 13, 14 and 15 can, for example, be roller bearing members of the commercially known type which are obtainable from skilled manufacturers in mass production with the standard dimensions and quality.

Finally, it should be mentioned that the invention is not limited to the illustrated construction applicable to four-cylinder pumps. The features of the invention may also advantageously be embodied in pumps having, say,

eight cylinders. Furthermore, the roller bearings 13 and 15 may be omitted, for example in pumps operating with average pressures.

We claim:

1. A piston pump whicn includes, in combination, a pump housing, a rotary drive shaft enclosed by said housing, a sole eccentric provided on said drive shaft, a plurality of pump units spaced about and secured to the periphery of said housing, said units extending radially with respect to the axis of said shaft, a delivery piston enclosed by and arranged to reciprocate in each of said pump units, at least two intermediate rings embracing and arranged side by side on said sole eccentric, th ough the medium of which the delivery pistons are successively driven from the eccentric, said pump units being arranged in pairs relatively oitset along the axis of the drive shaft and circumferentially offset with respect to the drive shaft, each pair comprising only two units being diametrically opposite to one another, and the side by side arrangement of said intermediate rings being such that each of them has bearing thereon only the delivery pis tons of one such pair of pump units.

2. A piston pump which includes, in combination, a pump housing, a rotary drive shaft enclosed by said housing, a sole eccentric provided on said drive shaft, a plurality of pump units spaced about and secured to the periphery of said housing, said units extending radially with respect to the axis of said shaft, a delivery piston enclosed by and arranged to reciprocate in each of said pump units, at least two intermediate rings embracing and arranged side by side on said sole eccentric and through the medium of which the delivery pistons are successively driven from the eccentric, said pump units being arranged in pairs relatively offset along the axis of the drive shaft and circumierentially offset with respect to the drive shaft, the two units of each pair being diametrically opposite to one another, and the side by side arrangement of said intermediate rings being such that each of them has bearing thereon the delivery pistons of one such pair only of pump units, and elements which are disposed between the intermediate rings themselves and also between the relevant ring ends and adjacent parts of the pump housing to maintain the said rings in correct positions axially on the eccentric.

3. A piston pump according to claim 2, wherein at least some of the said elements maintaining the intermediate rings in position on the eccentric are in the form of spacing plates.

4. A piston pump according to claim 2, wherein at least some of the said elements maintaining the intermediate rings in position on the eccentric are axial thrust. bearings.

5. A piston pump which includes, in combination, a pump housing, a rotary drive shaft enclosed by said housing, a sole eccentric provided on said drive shaft, four pump units spaced about and secured to the periphery of said housing, said units extending radially with respect to the axis of said shaft in a cruciform arrangement, a delivery piston enclosed by and arranged to reciprocate in each of said pump units, and two intermediate rings embracing and arranged side by side on said sole eccentric and through the medium of which the delivery pistons are successively driven from the eccentric, said pump units being arranged in two pairs so relatively offset along the axis of the drive shaft as to be respectively in alignment with the two intermediate rings, the two units of each pair being diametrically opposite to one another, the units being relatively disposed at right angles and each of the said two intermediate rings having bearing on it the two delivery pistons of one of the two pairs only of such pump units.

6. A piston pump which includes, in combination, a pump housing, a rotary drive shaft enclosed by said housing, a sole eccentric provided on said drive shaft, a plurality of pump units spaced about and secured to the periphery of said housing, said units extending radially with respect to the axis of said shaft, a delivery piston enclosed by and arranged to reciprocate in each of said pump units, at least two intermediate rings embracing and arranged side by side on said sole eccentric and through the medium of which the delivery pistons are successively driven from the eccentric, and a circular series of rolling bodies interposed between each intermediate ring and the eccentric, said pump units being arranged in pairs so relatively offset along the axis of the drive shaft and circumferentially offset with respect to the drive shaft, as to be respectively in alignment with the intermediate rings, the two units of each pair being diametrically opposite to one another and each of the intermediate rings having bearing on it the two delivery pistons of one of the pairs only of such pump units.

7. A piston pump which includes, in combination, a pump housing, a rotary drive shaft enclosed by said housing, a sole eccentric provided on said drive shaft, four pump units spaced about and secured to the periphery of said housing, said units extending radially with respect to the axis of said shaft in a cruciform arrangement, a delivery piston enclosed by and arranged to reciprocate in each of said pump units, two intermediate rings embracing and arranged side by side on said sole eccentric and through the medium of which the delivery pistons are successively driven from the eccentric, said pump units being arranged in two pairs so relatively ofiset along the axis of the drive shaft as to be respectively in alignment with the two intermediate rings, the two units of each pair being diametrically opposite to one another, the units being relatively disposed at right angles and each of the said two intermediate rings having bearing on it the two delivery pistons of one of the two pairs only of such pump units, a circular series of axial thrust roller bearings interposed between the opposed inner ends of the two intermediate rings, a spacing plate provided between the outer end of each such ring and an adjacent part of the pump housing and further circular series of axial thrust roller bearings interposed between said spacing plates and said outer ends of the two intermediate rings.

8. A piston pump which includes, in combination, a pump housing having therein a central suction chamber and co-axial with but separated from the latter a central compression chamber, a rotary drive shaft enclosed by said housing and extending through said suction chamber, a sole eccentric provided on said drive shaft, a plurality of pump units spaced about and secured to the periphery of said housing, said units extending radially with respect to the axis of said shaft, a delivery piston enclosed by and arranged to reciprocate in each of said pump units, a valve unit comprising a suction valve and a compression valve incorporated in each of the pump units, suction ducts provided in the pump units and in the pump housing for connecting the pump units with said central suction chamber, compression ducts also provided in the pump units and in the pump housing for connecting the pump units with said central compression chamber, two nipples communicating with the said suction and compression chambers and adapted for connection to a liquid supply container and a utility point respectively, and at least two intermediate rings embracing and arranged side by side on said sole eccentric and through the medium of which the delivery pistons are successively driven from the eccentric, said pump units being arranged in pairs relatively ofiset along the axis of the drive shaft and circumferentially offset with respect to the drive shaft, the two units of each pair being diametrically opposite to one another, .and the side by side arrangement of said intermediate rings being such that each of them has bearing thereon the delivery pistons of one such pair only of pump units.

9. A piston pump according .to claim 8, wherein a circular series of rolling bodies is interposed between each intermediate ring and the eccentric.

10. A piston pump according to claim 8, wherein elements are disposed between the intermediate rings themselves and also between relevant ring ends and adjacent parts of the pump housing to maintain the said rings in their correct positions on the eccentric.

11. A piston pump according to claim 8 and furnished with four pump units and two side-by-side intermediate rings, said pump including a circular series of axial thrust roller bearings interposed between the opposed inner ends of the [two intermediate rings, a spacing plate provided between the outer end of each such ring and an adjacent part of the pump housing and further circular series of axial thrust roller bearings interposed between said spacing plates and said outer ends of the two intermediate nngs.

References Cited in the file of this patent UNITED STATES PATENTS 1,778,238 Wilsey Oct. 14, 1930 2,635,544 Lossau Apr. 21, 1953 2,650,543 Pauget Sept. 1, 1953 2,702,008 Stoclrard Feb. 15, 1955 2,709,422 Bray May 31, 1955 2,801,596 Sewell Aug. 6, 1957 2,980,024 Pope Apr. 18, 1961 3,002,462 Raymond Oct. 3, 1961 3,066,610 Swanson Dec. 4, 1962 FOREIGN PATENTS 855,690 France May 17, 1940 847,850 Germany June 26, 1952 264,604 Great Britain Jan. 27, 1927 OTHER REFERENCES German Specification 1,096,750, Jan. 5, 1961. 

1. A PISTON PUMP WHICH INCLUDES, IN COMBINATION, A PUMP HOUSING, A ROTARY DRIVE SHAFT ENCLOSED BY SAID HOUSING, A SOLE ECCENTRIC PROVIDED ON SAID DRIVE SHAFT, A PLURALITY OF PUMP UNITS SPACED ABOUT AND SECURED TO THE PERIPHERY OF SAID HOUSING, SAID UNITS EXTENDING RADIALLY WITH RESPECT TO THE AXIS OF SAID SHAFT, A DELIVERY PISTON ENCLOSED BY AND ARRANGED TO RECIPROCATE IN EACH OF SAID PUMP UNITS, AT LEAST TWO INTERMEDIATE RINGS EMBRACING AND ARRANGED SIDE BY SIDE ON SAID SOLE ECCENTRIC, THROUGH THE MEDIUM OF WHICH THE DELIVERY PISTONS ARE SUCCESSIVELY DRIVEN FROM THE ECCENTRIC, SAID PUMP UNITS BEING ARRANGED IN PAIRS RELATIVELY OFFSET ALONG THE AXIS OF THE DRIVE SHAFT AND CIRCUMFERENTIALLY OFFSET WITH RESPECT TO THE DRIVE SHAFT, EACH PAIR COMPRISING ONLY TWO UNITS BEING DIAMETRICALLY OPPOSITE TO ONE ANOTHER, AND THE SIDE BY SIDE ARRANGEMENT OF SAID INTERMEDIATE RINGS BEING SUCH THAT EACH OF THEM HAS BEARING THEREON ONLY THE DELIVERY PISTONS OF ONE SUCH PAIR OF PUMP UNITS. 